Recently, a great variety of electronic devices such as smart phones, tablet personal computers (PCs), digital cameras, Moving Picture Experts Group phase 1 or phase 2 (MPEG-1 or MPEG-2) audio layer III (MP3) players, and electronic books have been widely used. Normally, such an electronic device may be connected to an external output device (e.g., an earphone, a headset, etc.) and may support the output of an unbalanced type earphone being capable of a wired call. In general, the electronic device may support a microphone (MIC) embedded in the external output device and, even though no MIC is embedded in the external output device, may support the output of an unbalanced audio signal. Also, the electronic device may have therein a connector joint part (e.g., a socket, a receptacle) for the connection with a connector (e.g., an ear jack) of an earphone, and the ear jack of the earphone may be formed of a 4-pole terminal. The 4-pole terminal may be designed as a standard terminal for supporting the unbalanced type earphone being capable of a wired call. Earphones may be classified into an unbalanced type and a balanced type. Generally, a balanced type earphone may output audio with high performance in comparison to an unbalanced type earphone.
Audio signals transmitted by the electronic device may be classified into a balanced type audio signal and an unbalanced type audio signal. Such different types of audio signals require different configurations of an output terminal. For example, unbalanced type audio signals may be formed of R signal, L signal, G signal and M signal, whereas balanced type audio signals may be formed of L+ signal, L− signal, R+ signal and R− signal. Normally, the electronic device fails to support audio signals based on a balanced type. Therefore, even though a balanced type earphone or headset is connected, the electronic device can hardly output high quality audio based on a balanced type.
Meanwhile, in order to support a balanced type output device (e.g., an earphone, a headset, etc.), a converter device may be further required. Namely, the electronic device needs an additional converter device so as to be compatible with the balanced type output device. The additional converter device may receive an unbalanced audio signal from the electronic device and then output an signal by performing a phase inversion from a signal of a right channel (a right output part) or of a left channel (a left output part) to a plus (+) signal or a minus (−) signal through a differential amplifier equipped therein.
The above information is presented as background information only to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the present disclosure.